Study examines waterflow effect on dams

(Host) More
than 70 large dams on the Connecticut River control the flow of water and they accomplish different goals,
such as generating electricity and mitigating the impact of floods.

But a new
study on the river is investigating whether water could flow more naturally
without hampering these dams.

As part of
a collaboration with Northeast public radio stations, Nancy Cohen from WNPR
reports on an effort to restore threatened floodplains, an ecosystem that can
soften the blow of floods.

(Cohen) Inside the
Union Village Dam gatehouse in Thetford, Vermont, hydraulic engineer Greg Hanlon of the U.S. Army
Corps of Engineers points to two hulks of metal.

(Hanlon) "These two here, they operate 8 foot by 12
foot steel gates that can close off or
open the conduit to varying degrees. "

(Cohen) On this fall
day the floodgates are open. The water that flows in from a tributary of the Connecticut River flows out. Just like an undammed river. But when
there's a threat of flooding the gates are lowered.

(Hanlon) "During the spring when we have downstream
concerns or high rain events we would operate these fairly frequently."

(Cohen) The Connecticut River has had its share of floods. After the devastating
flood of 1936 the federal government decided to put flood control dams on the
river. But besides dams, floodplains form a natural buffer against floods.

Forest ecologist Christian Marx of the Nature Conservancy is
pulling a measuring tape around a stout silver maple on a wide floodplain in East Hartford, Connecticut.

(Marx) "So this a nice one. This is 612 centimeters
circumference. That could be the biggest one we've found yet."

(Cohen) This tree is
more than 20 feet around. As part of a study conducted by the Nature Conservancy
and the U.S. Army Corps of Engineers, Marx is trying to figure out where the
healthy floodplains are on the Connecticut
River and how much water
they need. He says when the river floods it carries sediment and nutrients
which feed the lush floodplain forests.

(Marx) "All the resources that a tree needs to grow
are really abundant here. And so you get
these really luxurious forests, kind of like a tropical rainforest, big trees,
the herbs in the understory can be as tall as a man."

(Cohen) Marx isn't
exaggerating.

I'm walking through
six-foot, seven foot high nettles, which usually grow much smaller in my
experience. And there was poison ivy, vines and all kinds of stuff.

This kind of no-man's
land is good for wildlife. Wood ducks and mergansers nest in tree cavities.
Muskrats burrow on the river's edge.

Standing upstream on a
bridge over the river in Massachusetts Kim Lutz of the Nature Conservancy says
floodplains also benefit humans.

(Lutz) "They are the first buffer when a flood is
coming down the river that provides that water storage. It slows down the river
and protects human development along river systems."

(Cohen) Many of the
floodplains were lost long ago when the major cities on the Connecticut River were built and farm fields were ploughed. Roughly
half of the floodplain acreage in the river basin has been lost to development
and farms fields, said Lutz.

(Lutz) "Also there are forests that have changed
because the flow has changed whereas there might be a forest that's high and
dry it used to be a wet forest due to dam management. "

(Cohen) Researchers
from the Nature Conservancy and the Army Corps are building a computer model
that simulates how all the dams on the river operate now. And whether it's
possible to provide more environmental benefits without infringing on human
uses like hydro power, recreation and flood control.

(Hanlon) "There's a fine line between flooding a field
and flooding a house next to the field, so it's a very tight balancing act."

(Cohen) Hydraulic
engineer Greg Hanlon of the army Corps of Engineers says the Corps has already
altered the flow of water to benefit the environment.

(Yanlon) "We may be getting to the point that we've
done all that we can do without sacrificing our main mission of flood control.
Maybe not. And maybe these models will help us push the grey area a little more
to the environmental side or maybe not."

(Cohen) Ultimately
Hanlon says it's the corps that has to answer to the public in the wake of a
flood. But the Nature Conservancy says the ecosystems also deserve an answer.

Note: Tomorrow,
we'll have a report about a unique effort to raise public awareness of the Connecticut River's importance to our region.

Northeast
environmental coverage is part of NPR's local news initiative. The reporting is
funded, in part, by a grant from United Technologies.